The simplest test is manual: open ChatGPT, Gemini, Claude and Perplexity and ask the questions your customers would ask. "What is the best [your category] in [your region]?", "What is [your service]?", "Who is the leading reference in [your industry]?". Note whether your brand shows up, how it shows up and with what sentiment.
For continuous monitoring, there are tools that automate this process. app.netlinks.com.br, for example, runs periodic prompts across multiple AIs and records whether the brand was cited, in what context and how often. This lets you track the evolution over time and measure the impact of your GEO actions.
Beyond direct monitoring, indirect indicators help: an increase in branded searches on Google (people look up the company name after seeing the citation in the AI), growing direct traffic and leads who mention "I saw it on ChatGPT" or "the AI recommended you" as their source.